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pH CONTROLLED YEAST PROPAGATION

a technology of yeast and controllable growth, applied in the field of yeast propagation process, can solve the problems of yeast growth inhibited by acetic acid and/or sugar degradation products, excess yeast production (129,000 tons of feed yeast) and achieve the effect of avoiding excess production of yeas

Inactive Publication Date: 2015-09-10
DSM IP ASSETS BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides a process for propagating yeast using lignocellulosic hydrolysate as a carbon source. The process is stable, can be operated in multiple cycles, and avoids excess production of yeast. The advantage of this process is that the yeast is adapted during propagation on hydrolysate in such a way that its performance in ethanol fermentation of hydrolysate is increased compared to yeast not propagated in this way.

Problems solved by technology

Disadvantage of this known process is that since xylose rich stillage is used for biomass formation, excess yeast (129,000 tons of feed yeast) is produced.
Disadvantage to all currently known propagation process on acidic lignocellulosic hydrolysate is that yeast growth is inhibited by acetic acid and / or sugar degradation products.

Method used

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  • pH CONTROLLED YEAST PROPAGATION
  • pH CONTROLLED YEAST PROPAGATION
  • pH CONTROLLED YEAST PROPAGATION

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0092]In example 1, as lignocellulosic hydrolysate, enzymatically hydrolyzed pretreated corn stover (17% dry matter) was used. The composition of the hydrolysate is given in table 1.

TABLE 1Composition of the lignocellulosic hydrolysate(HPLC (H-column) analysis)Glucose(g / l)69.8Xylose(g / l)43.4Glycerol(g / l)0.2Formic acid(g / l)0.2Acetic acid(g / l)5.1Ethanol(% vol)0HMF(g / l)0.19Furfural(g / l)0.98Arabinose(g / l)5.2

Fermentation Parameters

[0093]A fed batch propagation reactor (1500 ml ) was filled with 709 g 5 times diluted lignocellulosic hydrolysate. There was added 0.2 g / l MgSO4, 1.1 g / l (NH4)2SO4, 4.5 g / l urea, 4 ml / l vitamin solution and 4 ml / l trace elements (As in Verduyn et al, 1992, ref. see below). The pH was adjusted to 5 with NH4OH. Temperature was of the fed batch reactor was controlled at 32° C. Dissolved oxygen levels were kept above 9% by aeration at 3 vvm (final volume) in combination with a stirring cascade (controlled between 200-700 rpm). Starting volume of the propagation ex...

example 2

[0098]In example 2, as lignocellulosic hydrolysate, enzymatically hydrolyzed pretreated corn stover (17% dry matter) was used. The composition of the hydrolysate is given in table 2.

TABLE 2Composition of the lignocellulosic hydrolysate(HPLC (H-column) analysis)Glucose(g / l)68.2Xylose(g / l)44.8Glycerol(g / l)0.0Formic acid(g / l)0.3Acetic acid(g / l)5.2Ethanol(% vol)0HMF(g / l)0.18Furfural(g / l)1.02Arabinose(g / l)5.2

Fermentation Parameters

[0099]A fed batch propagation reactor (1500 ml) was filled with 709 g 5 times diluted lignocellulosic hydrolysate. There was added 0.2 g / l MgSO4, 1.1 g / l KH2PO4, 4.5 g / l urea, 4 ml / l vitamin solution and 4 ml / l trace elements (As in Verduyn et al, 1992, ref. see below). The pH was of the hydrolysate (4.3) was not adjusted after enzymatic hydrolysis. Temperature was of the fed batch reactor was controlled at 32° C. Dissolved oxygen levels were kept above 9% by aeration at 3 vvm (final volume) in combination with a stirring cascade (controlled between 200-700 rpm...

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Abstract

The invention relates to a process for the aerobic propagation of yeast wherein the yeast is grown in a reactor, comprising the following steps:a) filling the reactor with carbon source and an initial yeast population,b) optionally growing the initial yeast population in the reactor in batch mode,c) measuring the pH in the reactor,d) adding lignocellulosic hydrolysate to the reactor in fed batch mode at a rate to set the pH in the reactor at a predetermined value,ande) after sufficient propagation, isolation of yeast from the reactor.The invention further relates to yeast propagated according to that propagation process and to a process for the production of fermentation product wherein sugar comprising hexose and pentose is anaerobically fermented to fermentation product with the propagated yeast.

Description

FIELD OF THE INVENTION[0001]The invention is directed to a propagation process for yeast. In particular the invention relates to a propagation process wherein yeast is propagated on lignocellulosic hydrolysate.BACKGROUND OF THE INVENTION[0002]There are nowadays processes proposed to use lignocellulosic material as a source for the production of fuel and of base chemicals. They are aimed at commercially-viable production of these products from lignocellulosic feedstocks.[0003]In such processes lignocellulosic material may for example be pretreated, then hydrolysed and subsequently the resulting hydrolysate that comprises hexose and / or pentose sugar may be converted by yeast into fermentation product. These processes may take place in a large scale Integrated Bioprocess Facility (IBF). The yeast fermentation is usually conducted under anaerobic conditions in the fermentation part of the IBF.[0004]To be able to supply enough yeast to the fermentation, yeast is propagated either in the ...

Claims

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Application Information

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IPC IPC(8): C12N1/16C12P7/06C12N1/22
CPCC12N1/16C12P7/06C12N1/22C12P7/10C12P7/16Y02E50/10
Inventor DE BRUIJN, HANS MARINUS CHARLES JOHANNESKLAASSEN, PAUL
Owner DSM IP ASSETS BV
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